1. Field of the Invention
Present invention relates to a two-frame reproducing apparatus which is improved by a developing element of a developing device being provided in such a manner that it can be separated from an image forming surface.
2. Description of the Prior Art
The internal functions and the composition thereof in a conventional electrophotographic reproducing apparatus are as shown in FIG. 1.
In the diagram, recording paper P which is supplied by first paper-feeding roller 3, sheet by sheet, from a paper-feeding cassette 2 mounted on a reproducing machine 1 is inverted after passing through a sub paper-feeding roller 3a and reaches a second paper-feeding roller 4. The timing and speed of conveyance of the paper are adjusted so that the fore end of the paper can fall in line with the fore end of a toner image formed on a photosensitive drum 5 which will be described below.
The photosensitive drum 5, which is given an electric charge uniformly on the peripheral surface thereof by a charging electrode 6 beforehand, rotates in the direction of the arrow. Meanwhile, an image of a document D which is moved horizontally in synchronization with the peripheral velocity of said drum 5 is transmitted onto the peripheral surface of the drum 5 by an exposure lamp 7 and a converging phototransmission element (tradename: SELFOC Lens) 8, and an electrostatic latent image is formed sequentially on said surface.
With the subsequent rotation of said photosensitive drum 5, the latent image on this drum is developed into a visible toner image by the developing element of a developing device 9, i.e. a developing sleeve 9a.
The photosensitive drum 5 rotates further and comes in contact with said recording paper P and the toner image on the drum 5 is transferred onto the paper P by a transfer electrode 10. Thereafter the recording paper P is separated from the drum by a separation electrode 11.
The recording paper P thus separated is fed to a fixing roller 13 via a conveying roller 12, and the toner image is molten and fixed on the paper by the roller 13. Then, the paper is ejected by an ejection roller 14 from paper ejection port 15 into an ejected paper tray, not shown in the diagram, which is provided outside the reproducing machine 1.
After the separation of the recording paper P, the photosensitive drum 5 rotates further in the direction of the arrow and the electric charge thereon is eliminated by a charge elimination electrode 16. Thereafter the residual toner adhering to the drum 5 is scraped down by a cleaning blade 17a of a cleaning device 17, and the toner thus scraped is collected in a cleaner box 18. Meanwhile, the photosensitive drum 5 is given another electric charge by the charging electrode 6 so that another electrostatic latent image may be formed thereon from a subsequent document.
Numeral 19 denotes a port into which the recording paper is inserted when it is supplied manually to the machine, and 3b denotes a paper-feeding roller which operates when the paper is supplied manually.
In the electrophotographic reproducing machine having these functions, the photosensitive drum 5 which suffers deterioration of performance or damage of the surface in employment and the cleaning blade 17a, the performance of which tends to deteriorate with abrasion, must be replaced periodically, and a developer cartridge 9b must be supplied frequently with toner. Therefore, these members have removable structures. Among them, the photosensitive drum 5 is disposed very close to the developing sleeve 9a since the latent image on the drum 5 is developed by a developer adhering to the sleeve 9a, and these two members must be in close proximity to each other, particularly when a one-component developer is used. Accordingly, the greatest possible care must be taken so that the photosensitive drum is not damaged by contact between the drum 5 and the developing device 9 when either of them is mounted or removed.
To facilitate handling these members, a number of constructions have been proposed. Among them, there are a construction in which a device enabling the manual withdrawal of the developing device 9 prior to the removal of the photosensitive drum 5 is provided, a construction in which the developing device 9 is pulled out along a guide rail when it is separated from the drum 5, and a construction in which the developing device 9 is moved away from the drum 5 by utilizing a device which is used for moving the developing device 9 when the reproducing machine is warmed up, etc. Every one of these systems, however, necessitates expensive components such as a solenoid and also many structural components including a lever and others, all of which add to the cost of the device. Also all of these systems are operated manually, so that there is always a chance for accidents caused by human error.
Such problems as described above are also unavoidable for a two-frame reproducing machine in which an upper frame 1a is coupled with a lower frame 1b in such a manner that the former can be opened and closed around a hinge as the center of its rotation, as shown in FIG. 1, for convenience for replacement or repair of components, or for trouble shooting.